Fuel cell type SO₂ sensor based on Cu/CF-N sensing electrode and Nafion proton conductor at room temperature

In this work, nitrogen doped carbon fiber loaded copper (Cu/CF-N) sensing electrode and Nafion proton conductor are used to fabricate fuel cell type gas sensors that realize fast response/recovery for SO2 detection at room temperature. This is the first time that this type of sensor has been used to detect SO2. We investigated the effect of Cu content on sensors' performance, and found that the Cu (20 wt%)/CF based sensor exhibited the highest response. This can be attributed to the optimal Cu content, which exposes the most active sites. More-over, nitrogen was doped into electrode material to further improve the performance. Nitrogen atoms enhance the conductivity of the material and its ability to adsorb SO2. These are confirmed by the complex impedance measurement and TPD analysis. The upgraded Cu/CF-N fuel cell type gas sensor showed a response of -435.6 nA to 50 ppm SO2 and a low detection limit of 500 ppb. Significantly, the Cu/CF-N sensor demonstrated short response time (44 s) and recovery time (87 s) at room temperature. Furthermore, with the advantages of no power consumption, excellent selectivity and good repeatability, the fuel cell type gas sensors have broad prospects in the field of room temperature gas detection.